Past Kaanapali Beach and Lahaina, there are the coolest pools in the ocean called Olivine Pools. You will need to hike down steep rocks (which I suck at), but my little nieces and nephews did it last year, so you can do it! Haha. It was a little too busy for our liking when we went (everyone go away!), but, nonetheless, it is still such a fun spot in Maui.
Maui 2016: Olivine Pools from Sierra Charlesworth on Vimeo.
Last Year's Olivine Pools Post HERE
Lava Rocks and Snorkeling Cove